The present invention concerns a laser processing machine with a laser beam generator, a processing head movable relative to the generator, and a gas chamber containing a gas volume and connected to a gas compensating chamber, and in which the gas chamber at least partially provided a beam guidance chamber for the laser beam and is at least partially bounded by a extensible wall which is extensible and compressible with the motion of processing head relative to the laser beam generator.
Both the intensity and the shape of a laser beam are adversely affected by gases located in the beam path which absorb rays in the wavelength of the laser beam, for example, gases containing hydrocarbons. The resulting impairment becomes considerable in the case of laser processing machines, in which the laser beam has to cover a relatively long distance between the laser beam generator and the processing head. In order to avoid such impairment the laser beam usually is guided through a beam guidance chamber of the laser processing machine which is filled with a gas without harmful impurities.
The publication DE-U-295 09 648 describes a machine of this kind in which the gas chamber is bordered by bellows. In this case a part of the gas chamber serves as he beam guidance chamber, and another part as a secondary chamber which is connected with the beam guidance chamber; however, the laser beam does not pass through the secondary chamber which also is filled with gas. The gas chamber is connected by a flow connection with a compensating volume of gas in a gas supply tank, which is filled with gas under pressure. The gas from the gas supply tank enters the gas chamber at one end and leaves the gas chamber at the opposite end through a corresponding outlet. In this manner, the gas chamber is permanently washed with a gas having a desired composition and kept free from impurities. Of course, the operation of the previously known machine entails considerable gas consumption.
It is an object of the present invention to provide a novel laser processing machine with a substantially closed gas space of substantially constant volume which in part comprises an extensible and compressible conduit providing the laser beam path between the laser beam generator and processing head.
It is also an object to provide such a laser processing machine which can be fabricated readily and relatively economically.
Another object is to provide such a laser processing machine in which the interior volume of the closed chamber is automatically maintained substantially constant.